"5.15" (sometimes written "5:15" or "5'15") is a song written by Pete Townshend of British rock band The Who from their second rock opera, Quadrophenia (1973). The song reached #20 on the UK Singles Chart, while the 1979 re-release (accompanying the film and soundtrack album) reached #45 on the Billboard Hot 100.

Although written as "5.15" on the single cover, on the back cover of Quadrophenia (the album from which the song is taken) it is written as "5:15".

In the song, the main character Jimmy has taken the titular train to Brighton, consumed a lot of drugs, recollecting his life with the Mods, the cultural movement to which he belongs (even if he has dropped out for now), and their duels with the Rockers. Jimmy's memories are extremely disjointed, consisting mainly of anger, confusion, violence, sexual frustration, and rootlessness.

"5.15", like many of the songs from Quadrophenia, is self-referential - "M-m-m-my generation" is a line - and thus represents an angrily self-centered, teenage disconnection with society, family and the opposite sex. 'Jimmy' was "born in the war" (that is, World War II and its aftermath) and does not understand why he should care about it (or anything) in the context of his extravagant Mod values.

Year 15 (XV) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Caesar and Flaccus (or, less frequently, year 768 Ab urbe condita). The denomination 15 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.

"The Man" is a slang phrase that may refer to the government or to some other authority in a position of power. In addition to this derogatory connotation, it may also serve as a term of respect and praise.

The phrase "the Man is keeping me down" is commonly used to describe oppression. The phrase "stick it to the Man" encourages resistance to authority, and essentially means "fight back" or "resist", either openly or via sabotage.

The earliest recorded use^{[citation needed]} of the term "the Man" in the American sense dates back to a letter written by a young Alexander Hamilton in September 1772, when he was 15. In a letter to his father James Hamilton, published in the Royal Dutch-American Gazette, he described the response of the Dutch governor of St. Croix to a hurricane that raked that island on August 31, 1772. "Our General has issued several very salutary and humane regulations and both in his publick and private measures, has shewn himself the Man." ^{[dubious – discuss]} In the Southern U.S. states, the phrase came to be applied to any man or any group in a position of authority, or to authority in the abstract. From about the 1950s the phrase was also an underworld code word for police, the warden of a prison or other law enforcement or penal authorities.